The invention relates to a method and a device for firing at least one firing element for a restraining device in a motor vehicle.
Arrangements for firing a restraining device in a motor vehicle usually have a sensor for detecting an accident, a control device which is connected downstream of the sensor, the firing device which is arranged spatially separated from the control device and is connected to it via a line, and at least one firing element (for example a firing cap) for the restraining device, the firing element being electrically connected to the firing device.
If, for example, a plurality of firing caps are to be fired simultaneously in such a context using a firing command, but not all the firing caps detect the first firing command and/or fire, the transmission link which is usually embodied as a firing bus between the control device and the firing device may, under certain circumstances, be disrupted to such an extent that no further firing commands can be transmitted. This is the case, for example, if a short circuit or an interruption at the bus occurs as a result of individual undesired detonations. It is then no longer possible to fire the remaining firing caps since no further firing command can be transmitted.
The invention discloses a method and an arrangement for firing at least one firing element for a restraining device in a motor vehicle which provides a higher degree of immunity to faults.
In one embodiment of the invention, there are firing commands as the first to be transmitted repeatedly (for example 3 times), for firing to be delayed during this time, and for firing of the firing elements, for example by means of the first firing command, to be permitted after the multiple transmission.
In the embodiment, there is a method in which a firing command is transmitted, and then the firing command is transmitted n times, from a control device to a firing device for the firing element/elements, n being at least equal to 1. Then, the n+1 transmitted firing commands are evaluated in the firing device and the firing element or elements is/are fired by the firing device after the transmission of the last n+1, for example by the first firing command.
In one aspect of the invention, the firing actuation of the firing elements is preferably repeated at least once or, for the sake of simplicity, coupled to the number of transmitter firing commands in order to fire firing elements which have erroneously not yet been fired. Moreover, in addition to simultaneous firing of the plurality of firing elements, it is also possible to provide for the chronologically offset firing of the firing elements so that the firing elements are fired in succession.
In another embodiment of the invention, there is a device including a control device for generating n+1 identical firing commands, a firing device for firing the at least one firing element by connecting the firing signal to the firing element, and a transmission device for the transmission of the firing commands by the control device to the firing device. The firing element is not fired by the firing device until after the transmission of the last of the n+1 firing commands, for example by the first firing command.
In one aspect of the invention, in order to ensure that the firing of the firing element or elements takes place after the last of the n+1 firing commands has been transmitted, with the control device a delay device is provided for delaying the firing signal, the delay device being fired by the first firing command and having a delay which is longer than the time which is necessary for the transmission of the firing commands. The use of a delay device makes it possible for the firing element or elements to be operated in such a way that firing cannot disrupt the transmission of the firing commands and/or said firing elements are not made to fire until the firing signal has been repeated several times.
In another aspect of the invention, in order to be able to increase the immunity to faults further, the firing commands in the control device can be encoded and transmitted to the firing device in encoded form. The firing device contains a firing command decoder in order to decode the firing commands and to generate the firing signals for the firing elements from them.
In still another aspect of the invention, it is possible to provide for a plurality of firing elements to be fired in succession by the firing device in order to bring about more uniform loading of the power supply for the firing elements.